Basically I thought I’d put up what I’ve learnt to help anyone who needs it.
Sorry I don’t have any pics of the process but I diid this a long while ago
What had happened to me was whilst I was moving the window the green runner shattered and the window fell off the guide bracket.
WARNING - If the window does fall and you hear a crunching sound, don't try to press the window switch anymore and the regulator may be still be useable!